The present invention relates to an image-forming apparatus and method, and more particularly to an image-forming apparatus and method for preparing positive or negative films for use in making printing plates for offset lithography.
Recently, printing and plate-making technology have advanced remarkably, along with the progress of electronic technology. Today the electronic plate-making technique is dominant. Printing plates are made electronically in the following way. First, an original, with an image formed on it, is optically scanned. The light refelected from the original is converted into electrical signals representing the densities of the respective picture elements forming the image. These signals are converted into light beams of different intensities. The light beams are applied to a film (i.e., photosenstive material). The film, thus exposed, is developed, whereby a positive or negative film is prepared. The positive or negative is used to make a printing plate.
This method of preparing positive or negative films consists of many steps. The apparatus for performing this method is inevitably complicated, large and expensive. The conventional apparatuses can prepare one film for one color at a time. Further, since the apparatuses are designed for preparing films for making printing plates, they cannot be used for other purposes.